LiDAR Concepts Questions & Answers

What types of LiDAR concepts are being worked on, and is there a LiDAR design that’s better than others in the market?

First, Hamamatsu does not make LiDAR systems; instead, we supply LiDAR companies with critical optical components or assemblies used in the LiDAR system. Because Hamamatsu is supporting many unique LiDAR designs, we have a general awareness of the types of LiDAR concepts in the market today and those being discussed for the future.

As of spring 2021, I think many 905nm and 1550nm direct TOF (time of flight) concepts are proven and headed toward production, while long-range, high-resolution flash LiDAR or coherent LiDAR concepts like FMCW (frequency-modulated continuous wave) are being touted as future LiDAR concepts (see Fig. 1).

Also, I feel each LiDAR concept has its own benefits that make it best-suited for a specific use case, such as for ADAS, autonomous vehicles, robots, industrial automation, security, or other markets/applications. Therefore, I don’t believe there’s one concept that’s better than others.

Figure 1. Examples of LiDAR concepts

If I were to design a LiDAR system, how do I know which type of photodetector is the right one?

Well, this is a complex question to answer, and it really depends on the system-level requirements.

Generally, there are 4 types of detector technologies:

  • PIN diode
  • Avalanche photodiode (APD)
  • Silicon photomultiplier (SiPM) or MPPC (Multi-Pixel Photon Counter)
  • Single-photon avalanche diode (SPAD) or SPPC (Single-Pixel Photon Counter)

They can be offered either with silicon materials for the 850-940nm LiDAR concepts or InGaAs materials for the 1550nm LiDAR concepts. Each of these detector technologies is unique and has benefits suitable for different LiDAR concepts. See Table 1 below to get an idea of how the detectors are different from each other.

I would also suggest talking to Hamamatsu directly about the type of LiDAR design you are trying to make and the system-level requirements, so we can walk you through the different parameters of detectors, such as sensitivity, recovery time, dynamic range, noise, and more, to help you make the optimal choice.

Because Hamamatsu has all 4 photodetector technologies, we aren’t biased and wouldn’t attempt to sway you toward any one of these photodetectors. We understand the time to market is critical for a LiDAR company’s success, so we don’t want to steer you toward the wrong path that would be difficult to return from.

Visit our main website to see our photodetector technologies.

Comparison of photodetector technologies for LiDAR systems

Table 1: Comparison of photodetector technologies for LiDAR systems

What are the possible light sources to use for my LiDAR concept?

There are various light sources to consider depending on the LiDAR design, but generally, edge-emitting lasers or VCSELs are being considered for 850-940nm LiDAR concepts, and fiber lasers or DFB (distributed feedback) lasers for direct TOF or FMCW 1550nm LiDAR concepts.

When considering the right sources for 850-940nm LiDAR concepts, the edge-emitting lasers are good choices for a scanning type of LiDAR, and VCSELs are best for flash LiDAR concepts. Then for 1550nm, high-power fiber lasers or other types of high-power lasers are great for TOF LiDAR concepts, while FMCW LiDAR requires lasers with lower power but narrow linewidth.

The considerations for which laser product is best can be complex, depending on the various system-level requirements such as range, resolution, range error, and reliability. You must also consider light source factors such as NFP (near field pattern), peak power output, laser efficiency, linewidth, stability, and others.

The best way to pick the right laser is to let Hamamatsu know your system-level requirements, so we may provide recommendations for the best source.

What do you think is the biggest challenge for a LiDAR system when going from prototype to production?

There are several challenges that LiDAR startups or designers should consider even at the prototype stage, so they are prepared when the concept is ready for production.

For example, one of the main challenges is meeting the qualification and reliability requirements for an automotive-grade LiDAR system. Certain AEC and ISO standards are a must when the system is approved to be used in the harsh automotive environment. The various standards and qualifications create many headaches since most LiDAR concepts at the prototype stage are built with discrete components, which means complex supplier management as well as qualification needs. This is why more and more LiDAR system makers are moving toward more integrated assembly type of solutions. Fig. 2 below showcases Hamamatsu’s solutions—from discrete components to assemblies to modules—that are suitable depending on if the LiDAR system is at the prototype or production stage.

Another key challenge is the need for customization. LiDAR designs are different from each other, so the light sources, detectors, and assemblies will have different requirements from one LiDAR concept to the next. This poses challenges to suppliers, such as Hamamatsu, to be able to take on multiple customization requests from customers that want different detector, source, or assembly designs. The customizations could be as simple as changing the gap size between detector elements in an array, or as complex as adding new functions into an ASIC design or modifying the complete optical assembly that includes sources and detectors. Fortunately, Hamamatsu can provide simple to complex customization since more than 80% of our sales is based on custom designs.

Of course, there are more challenges than just the two I mentioned, and I’d love to talk to you more about this topic. Please contact us to further discuss these challenges or your customization needs.

Contact us.

Figure 2. Hamamatsu offers discrete components, assemblies, and modules for LiDAR systems. Customization available.

Meet the engineers

Jake Li is a Business Development Manager at Hamamatsu, working in the New Jersey office. He has been with Hamamatsu for 7 years and focuses on business development opportunities related to new Hamamatsu products such as silicon photomultiplier (or MPPC) and single-photon avalanche diode (or SPPC), as well as emerging markets such as LiDAR (light detection and ranging) for automotive, industrial automation, robotics, and other fields. He enjoys playing golf, snowboarding in the winter, and taking on new personal or professional challenges.

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